In Sales Document, Default item category propose by system automatically based on the below setting :-
Sales Documented Type
Sales Document distinguishes
different type of business processes represent in SAP system. Sales document
type determines how the system process in sales processing
Item Categories group from Material Master
A group of material
that have same Item categories. Based on this System automatically proposes an item category in the document.
For example, Third party item Or Normal item
Item usages
This item
usage indicator controls the system when you process a sales document item in a
certain context For example. the any text items and packing items,
Higher Level Item categories
Higher Level Item categories influence main item category of
the higher-level item determines the item category of related sub-items.
Based on the above
data records system propose default item category for the document
